Effects of Tilted Free-Stream on the Transonic Flow Past a Circular Cylinder
-
摘要: 采用大涡模拟方法数值研究了偏斜角为60°的偏斜圆柱跨声速绕流.基于非偏斜圆柱跨声速绕流的实验和数值研究工作,来流Mach数取为0.75,Reynolds数取为2×105.通过与相同参数的非偏斜圆柱跨声速绕流对比,分析了偏斜来流对柱体受力和流动特性的影响.由于偏斜来流的流动控制,偏斜圆柱的阻力比非偏斜圆柱的阻力减小高达45%,而振荡力仅受到较小的抑制.偏斜圆柱流场的可压缩性被弱化,激波和小激波消失,而整体流动的模态未改变.偏斜来流使得偏斜圆柱后的剪切层变得更为稳定,进而提升柱体背压.在剪切层的初始发展阶段,剪切层的扰动涡斜脱泻模态和快速动能衰减是偏斜圆柱剪切层更为稳定的两个主要原因.Abstract: The transonic flow past a tilted cylinder at an angle of 60°was investigated numerically with the large eddy simulation technique. Based on the previous experimental results and computational researches on transonic flow past the nontilted cylinder, the freestream Mach number was chosen as 0.75 and Reynolds number as 2×105. Compared with the transonic flow past a corresponding nontilted cylinder, effects of the tilted freestream on the force and flow characteristics of the tilted cylinder were analyzed. Because of flow control of the tilted freestream, the mean drag coefficient of the tilted cylinder is less than that of the nontilted cylinder with a drag reduction up to 45%, while less suppression of the fluctuating force is obtained. Fluid compressibility in the tilted cylinder flow is weakened due to elimination of shocks and shocklets, however, no change occurs in the whole flow modes. Owing to the tilted freestream, the shear layer shed from the tilted cylinder is more stable, which leads to a higher basepressure distribution. Two main mechanisms are associated with the more stable shear layer behind the tilted cylinder, i.e., the oblique vortexshedding mode and faster kineticenergy damping in the initial stage of shear layer developement.
-
Key words:
- circular cylinder /
- tilted cylinder /
- compressible turbulence /
- large eddy simulation /
- flow control
-
[1] Macha J M. Drag of circular cylinders a transonic Mach numbers[J].Journal of Aircraft,1977,14(6): 605-607. [2] Murthy V S, Rose W C. Detailed measurements on a circular cylinder in cross flow[J].AIAA Journal,1978,16(6): 549-550. [3] Rodriguez O. The circular cylinder in subsonic and transonic flow[J].AIAA Journal,1984,22(12): 1713-1718. [4] Xu C Y, Chen L W, Lu X Y. Effect of Mach number on transonic flow past a circular cylinder[J].Chinese Science Bulletin,2009,54(11): 1886-1893. [5] Xu C Y, Chen L W, Lu X Y. Numerical simulation of shock wave and turbulence interaction over a circular cylinder[J].Modern Physics Letters B,2009,23(3): 233-236. [6] 许常悦, 赵立清, 王从磊, 孙建红. 趋于临界马赫数的圆柱跨声速绕流特性分析[J]. 航空学报, 2012,33(11): 1984-1992.(XU Chang-yue, ZHAO Li-qing, WANG Cong-lei, SUN Jian-hong. Characteristics analysis of the transonic flow past a circular cylinder towards the critical Mach number[J].Acta Aeronautica et Astronautica Sinica,2012,33(11): 1984-1992.(in Chinese)) [7] 许常悦, 王从磊, 孙建红. 圆柱跨声速绕流中的激波/湍流相互作用大涡模拟研究[J]. 空气动力学学报, 2012,30(1): 22-27.(XU Chang-yue, WANG Cong-lei, SUN Jian-hong. Large eddy simulation of shock-wave/turbulence interaction in the transonic flow over a circular cylinder[J].Acta Aerodynamica Sinica,2012,30(1): 22-27.(in Chinese)) [8] Vlachos P P, Telionis D P. The effect of free surface on the vortex shedding from inclined circular cylinder[J].Journal of Fluid Engineering,2008,130(2): 021103. [9] Hogan J D, Hall J W. Experimental study of pressure fluctuations from yawed circular cylinder[J].AIAA Journal,2011,49(11): 2349-2356. [10] Meunier P. Stratified wake of a tilted cylinder—part 1: suppression of a von Krmn vortex street[J].Journal of Fluid Mechanics,2012,699: 174-197. [11] Moin P, Mahesh K. Direct numerical simulation: a tool in turbulence research[J].Annual Review of Fluid Mechanics,1998,30: 539-578. [12] Xu C Y, Zhao L Q, Sun J H. Large-eddy simulation of the compressible flow past a tabbed cylinder[J].Chinese Science Bulletin,2012,57(24): 3203-3210. [13] Xu C Y, Chen L W, Lu X Y. Large-eddy simulation of the compressible flow past a wavy cylinder[J].Journal of Fluid Mechanics,2010,665: 238-273. [14] Chen L W, Lu X Y, Xu C Y. Numerical investigation of the compressible flow past an aerofoil[J].Journal of Fluid Mechanics,2010,643: 97-126. [15] Chen L W, Lu X Y, Xu C Y. Large-eddy simulation of opposing-jet-perturbed supersonic flows past a hemispherical nose[J].Modern Physics Letters B,2010,24(13): 1287-1290. [16] Berkooz G, Holmes P, Lumley J L. The proper orthogonal decomposition in the analysis of turbulent flows[J].Annual Review of Fluid Mechanics,1993,25: 539-575. [17] Prasad A, Williamson C H K. The instability of the shear layer separating from a bluff body[J].Journal of Fluid Mechanics,1997,333: 375-402. [18] Zeman O. Dilatation dissipation:the concept and application in modeling compressible mixing layers[J].Physics of Fluids A,1990,2: 178-188. [19] Andreopoulos Y, Agui J H, Briassulis G. Shock wave-turbulence interactions[J].Annual Review of Fluid Mechanics,2000,32: 309-345.
点击查看大图
计量
- 文章访问数: 946
- HTML全文浏览量: 133
- PDF下载量: 800
- 被引次数: 0